In general, CRTs are designed to display colored images on a panel screen by exciting phosphors on the internal surface of the screen with electron beams emitted from an electron gun while varying the intensity of phosphor-excitation. A thin-metal shadow mask having a plurality of apertures is placed directly behind the screen to ensure that each beam hits the corresponding phosphor. That is, the shadow mask may act as a color selector to minimize the generation of spurious colors due to excitation of the wrong phosphor.
The shadow mask is mounted in the CRT panel with a support assembly. The support assembly includes a mask frame placed under the shadow mask to support it and a plurality of stud pins each embedded in the panel with a protruding portion. The support assembly further includes a plurality of springs for connecting the mask frame to the stud pins. Each of the springs has an end welded to the mask frame and an opposite end engaged with the protruding portion of the stud pin.
The spring is conventionally formed with a metal plate consisting of one element. However, with this structure, when external impacts or sonic waves from a Speaker are applied to the CRT, the resulting vibration energy is easily transmitted to the shadow mask sequentially through the stud pin and the spring. At this time, the shadow mask seriously vibrates due to its structural weakness so that the electron beam deviates from its correct progressing course and impinges upon wrong phosphors, causing spurious color images on the viewing screen.
Therefore, it is necessary that the spring should act as a connecting medium capable of minimizing or interrupting the vibration energy from the external.